LOUIS PASTEUR. 27 



one is familiar with the results. He discovered a method of ren- 

 dering the invading organisms of fowl cholera so impaired in their 

 action as to be unable to produce death, giving rise, on the con- 

 trary, simply to a slight indisposition ; but demonstration soon 

 showed him that this slight indisposition was followed by immunity 

 against the more severe disease. To anthrax he turned the same 

 line of investigation, and after patient, laborious search discovered 

 a means of rendering the anthrax germ impaired in its vigour. 

 His preliminary experiments convinced him that he had achieved 

 success, and then came one of those dramatic public exhibitions 

 in which Pasteur so delighted, and which have so impressed the 

 world. Almost before the public had learned that he had obtained 

 a possible method of preventing this dread disease among agricul- 

 turists, Pasteur made arrangements for a public test of his method, 

 and in the presence of an audience of some two hundred experts, 

 made up of physicians, veterinarians. Senators, prefects, farmers, 

 members of the French Academy, and others of high standing, he 

 demonstrated by a simple experiment, lasting about a week, that 

 he could, with unerring certainty, prevent cattle from acquiring 

 anthrax; that he could give to them a practically absolute immu- 

 nity against this almost surely fatal disease, by infecting them with 

 a very mild indisposition a few days before. The effect upon the 

 audience was electrical, and their enthusiasm knew no bounds. 



Pasteur's experiments spread at once over the world, and from 

 this further practical application of his scientific research his reputa- 

 tion made another advance. His anthrax vaccine was distributed 

 through the civilised world, was used by grazing communities 

 everywhere, and it has been thought to have saved the lives of 

 hundreds of thousands of cattle. The greatness of this discovery 

 can hardly be appreciated to-day. It was a logical discovery of a 

 new method of meeting disease. While other even more valuable 

 discoveries in the same line have followed and are still to follow, 

 none can equal in significance this first application of the studies 

 of the microscope to the treatment of disease. 



Following the work upon anthrax, various other lines of bacteri- 

 ological research connected with diseases of animals attracted his 

 attention and demanded his time. It was not, however, until he 

 had attacked the problem of the most dreaded of all human dis- 



